1. Field of the Invention
The disclosures herein generally relate to a liquid discharge head and an image forming apparatus including the liquid discharge head.
2. Description of the Related Art
An image forming apparatus of a printer, a facsimile machine, a copier, a plotter, or a multifunction peripheral (MFP) combining one or more of the above functions may be realized by an inkjet recording apparatus, which is a liquid discharge type image forming apparatus that uses a recording head made of a liquid discharge head (liquid droplet discharge head) that discharges liquid droplets, for example.
The liquid discharge type image forming apparatus forms (records or prints) an image by discharging ink droplets from the recording head onto a recording medium (paper sheet, OHP film, etc.) that is being transported. The image forming apparatus may be a serial-type image forming apparatus in which the recording head discharges liquid droplets while moving in the main scanning direction or a line-type image forming apparatus that uses a line-type recording head that discharges liquid droplets without moving.
The liquid discharge head supplies ink from an ink tank via a common liquid chamber to plural individual liquid chambers (e.g., pressure chamber, individual supply paths), and selectively applies pressure to the ink supplied to the individual liquid chambers to prompt liquid droplets to be discharged from a nozzle.
A nozzle hole of the liquid discharge head is typically arranged to be around several tens of micrometers (μm) in diameter. Thus, when some foreign particle gets mixed with the ink, the foreign particle may flow with the ink and get stuck in the nozzle to thereby cause a discharge defect.
In order to prevent clogging of the nozzle by such foreign particles, a filter for removing foreign particles and air bubbles is arranged at an ink supply path for supplying ink to the nozzle. Also, a damper for absorbing pressure variations is arranged in the common liquid chamber in order to prevent the transmission of pressure variations after discharging ink.
Various techniques are disclosed for arranging the filter and the damper on the same member (e.g., see Japanese Laid-Open Patent Publication Nos. 2003-311952, 2006-231812, and 2011-25663). By arranging the filter and the damper on the same member, fabrication processes may be simplified, for example.
Japanese Laid-Open Patent Publication No. 2003-311952 discloses an inkjet head that has a damper for absorbing pressure variations in a common ink chamber and a trap filter having fine through holes arranged on the same plate. Japanese Laid-Open Patent Publication No. 2006-231812 discloses a recording head that has a filter integrally formed with a damper arranged between a common liquid chamber and individual liquid chambers. Japanese Laid-Open Patent Publication No. 2011-25663 discloses a liquid injection head that has a damper and a filer section formed on a first layer of a vibrating plate member that forms a part of the walls of individual liquid chambers.
Conventionally, a filter needs to have high stiffness in order to prevent the filter from breaking. On the other hand, since a damper absorbs pressure variations, it needs to have high compliance, which is the inverse of stiffness and is an indicator of elasticity and flexibility.
Even in the case of forming a filter and a damper on the same member, the filter needs to have high stiffness and the damper needs to have high compliance.
However, the above disclosures do not contemplate arranging the filter to have high stiffness and arranging the damper to have high compliance in forming the filter and the damper on the same member. Thus, when the damper is arranged to have adequately high compliance for achieving desired performance, the stiffness of the filter may be inadequate, and the filter may be prone to breaking.